Error sources, compensation, and probe path optimization for on-machine metrology of freeform optics

As on-machine metrology for freeform optics becomes increasingly popular, error analysis and compensation techniques and probe path optimization must evolve in response. For this work, a four axis Moore Nanotech Universal Measuring Machine (based on a diamond turning machine design) is used with a Precitec chromatic confocal probe. The system is set up in a thermally controlled enclosure, and a LabVIEW data acquisition program is used to record probe data, time, and machine positioning data directly from the machine scales. Issues addressed include probe testing and calibration, thermal errors, data age, compensation methods, and probe path optimization for error reduction. The combined error reduction/compensation approach improves on-machine metrology for freeform optics.